Hops (Humulus lupulus) is a climbing perennial plant native to North America. It is best known as a flavoring agent in beer but has many other culinary and medicinal uses as well. While it is generally recognized as safe by the FDA, hops may be more likely to cause side effects when taken in larger quantities, according to Drug Information Online 1. Learning about the side effects of hops allows you to use it more safely for maximum benefit.

Drowsiness

Hops can be found in some multi-herb supplements for insomnia or nervousness. Like other calming herbs, hops may cause drowsiness in some people. Taking larger doses or combining hops with other sedating herbs or medications may increase the risk of drowsiness. For this reason, The University of Pittsburgh Medical Center warns patients to avoid using hops while taking sleep aids, anti-anxiety drugs and similar medications.

Estrogenic Effects

Like soy, hops contains phytoestrogens -- plant-based substances that mimic the effects of estrogen in the body. While not harmful for most people, phytoestrogens like those in hops may not be safe for patients with a history of breast cancer or other estrogen-related conditions. The University of Pittsburgh Medical Center advises pregnant women and those with kidney or liver disease to avoid using hops until more is known about its safety.

Allergic Reactions

Hops can act as an allergy trigger in some people. Pollen Library lists hops as a moderate allergen along with plants like cedar elm and California juniper. Typical nasal allergy symptoms like sneezing, congestion or runny nose may occur after ingesting hops or inhaling its pollen. Rarely, a life-threatening reaction known as anaphylaxis can occur after ingesting hops. Signs of anaphylaxis include low blood pressure, throat swelling and trouble breathing.

Prevention/Solution

When used as directed, hops is not likely to cause dangerous side effects in most people. To further ensure safety, read dosing directions carefully before taking hops and stop using it if you experience bothersome side effects. Ask a doctor before using hops if you take other drugs or supplements that cause drowsiness and avoid driving until you know how hops affects you. If you experience sudden or severe symptoms like rapid heartbeat or throat swelling, seek immediate medical attention.